1// SPDX-License-Identifier: GPL-2.0
2/*
3 *  mm/mprotect.c
4 *
5 *  (C) Copyright 1994 Linus Torvalds
6 *  (C) Copyright 2002 Christoph Hellwig
7 *
8 *  Address space accounting code	<alan@lxorguk.ukuu.org.uk>
9 *  (C) Copyright 2002 Red Hat Inc, All Rights Reserved
10 */
11
12#include <linux/pagewalk.h>
13#include <linux/hugetlb.h>
14#include <linux/shm.h>
15#include <linux/mman.h>
16#include <linux/fs.h>
17#include <linux/highmem.h>
18#include <linux/security.h>
19#include <linux/mempolicy.h>
20#include <linux/personality.h>
21#include <linux/syscalls.h>
22#include <linux/swap.h>
23#include <linux/swapops.h>
24#include <linux/mmu_notifier.h>
25#include <linux/migrate.h>
26#include <linux/perf_event.h>
27#include <linux/pkeys.h>
28#include <linux/ksm.h>
29#include <linux/uaccess.h>
30#include <linux/mm_inline.h>
31#include <linux/pgtable.h>
32#include <linux/sched/sysctl.h>
33#include <linux/userfaultfd_k.h>
34#include <linux/memory-tiers.h>
35#include <asm/cacheflush.h>
36#include <asm/mmu_context.h>
37#include <asm/tlbflush.h>
38#include <asm/tlb.h>
39
40#include "internal.h"
41
42bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
43			     pte_t pte)
44{
45	struct page *page;
46
47	if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
48		return false;
49
50	/* Don't touch entries that are not even readable. */
51	if (pte_protnone(pte))
52		return false;
53
54	/* Do we need write faults for softdirty tracking? */
55	if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte))
56		return false;
57
58	/* Do we need write faults for uffd-wp tracking? */
59	if (userfaultfd_pte_wp(vma, pte))
60		return false;
61
62	if (!(vma->vm_flags & VM_SHARED)) {
63		/*
64		 * Writable MAP_PRIVATE mapping: We can only special-case on
65		 * exclusive anonymous pages, because we know that our
66		 * write-fault handler similarly would map them writable without
67		 * any additional checks while holding the PT lock.
68		 */
69		page = vm_normal_page(vma, addr, pte);
70		return page && PageAnon(page) && PageAnonExclusive(page);
71	}
72
73	/*
74	 * Writable MAP_SHARED mapping: "clean" might indicate that the FS still
75	 * needs a real write-fault for writenotify
76	 * (see vma_wants_writenotify()). If "dirty", the assumption is that the
77	 * FS was already notified and we can simply mark the PTE writable
78	 * just like the write-fault handler would do.
79	 */
80	return pte_dirty(pte);
81}
82
83static long change_pte_range(struct mmu_gather *tlb,
84		struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr,
85		unsigned long end, pgprot_t newprot, unsigned long cp_flags)
86{
87	pte_t *pte, oldpte;
88	spinlock_t *ptl;
89	long pages = 0;
90	int target_node = NUMA_NO_NODE;
91	bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
92	bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
93	bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
94
95	tlb_change_page_size(tlb, PAGE_SIZE);
96	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
97	if (!pte)
98		return -EAGAIN;
99
100	/* Get target node for single threaded private VMAs */
101	if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
102	    atomic_read(&vma->vm_mm->mm_users) == 1)
103		target_node = numa_node_id();
104
105	flush_tlb_batched_pending(vma->vm_mm);
106	arch_enter_lazy_mmu_mode();
107	do {
108		oldpte = ptep_get(pte);
109		if (pte_present(oldpte)) {
110			pte_t ptent;
111
112			/*
113			 * Avoid trapping faults against the zero or KSM
114			 * pages. See similar comment in change_huge_pmd.
115			 */
116			if (prot_numa) {
117				struct folio *folio;
118				int nid;
119				bool toptier;
120
121				/* Avoid TLB flush if possible */
122				if (pte_protnone(oldpte))
123					continue;
124
125				folio = vm_normal_folio(vma, addr, oldpte);
126				if (!folio || folio_is_zone_device(folio) ||
127				    folio_test_ksm(folio))
128					continue;
129
130				/* Also skip shared copy-on-write pages */
131				if (is_cow_mapping(vma->vm_flags) &&
132				    folio_ref_count(folio) != 1)
133					continue;
134
135				/*
136				 * While migration can move some dirty pages,
137				 * it cannot move them all from MIGRATE_ASYNC
138				 * context.
139				 */
140				if (folio_is_file_lru(folio) &&
141				    folio_test_dirty(folio))
142					continue;
143
144				/*
145				 * Don't mess with PTEs if page is already on the node
146				 * a single-threaded process is running on.
147				 */
148				nid = folio_nid(folio);
149				if (target_node == nid)
150					continue;
151				toptier = node_is_toptier(nid);
152
153				/*
154				 * Skip scanning top tier node if normal numa
155				 * balancing is disabled
156				 */
157				if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
158				    toptier)
159					continue;
160				if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
161				    !toptier)
162					folio_xchg_access_time(folio,
163						jiffies_to_msecs(jiffies));
164			}
165
166			oldpte = ptep_modify_prot_start(vma, addr, pte);
167			ptent = pte_modify(oldpte, newprot);
168
169			if (uffd_wp)
170				ptent = pte_mkuffd_wp(ptent);
171			else if (uffd_wp_resolve)
172				ptent = pte_clear_uffd_wp(ptent);
173
174			/*
175			 * In some writable, shared mappings, we might want
176			 * to catch actual write access -- see
177			 * vma_wants_writenotify().
178			 *
179			 * In all writable, private mappings, we have to
180			 * properly handle COW.
181			 *
182			 * In both cases, we can sometimes still change PTEs
183			 * writable and avoid the write-fault handler, for
184			 * example, if a PTE is already dirty and no other
185			 * COW or special handling is required.
186			 */
187			if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) &&
188			    !pte_write(ptent) &&
189			    can_change_pte_writable(vma, addr, ptent))
190				ptent = pte_mkwrite(ptent, vma);
191
192			ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
193			if (pte_needs_flush(oldpte, ptent))
194				tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
195			pages++;
196		} else if (is_swap_pte(oldpte)) {
197			swp_entry_t entry = pte_to_swp_entry(oldpte);
198			pte_t newpte;
199
200			if (is_writable_migration_entry(entry)) {
201				struct folio *folio = pfn_swap_entry_folio(entry);
202
203				/*
204				 * A protection check is difficult so
205				 * just be safe and disable write
206				 */
207				if (folio_test_anon(folio))
208					entry = make_readable_exclusive_migration_entry(
209							     swp_offset(entry));
210				else
211					entry = make_readable_migration_entry(swp_offset(entry));
212				newpte = swp_entry_to_pte(entry);
213				if (pte_swp_soft_dirty(oldpte))
214					newpte = pte_swp_mksoft_dirty(newpte);
215			} else if (is_writable_device_private_entry(entry)) {
216				/*
217				 * We do not preserve soft-dirtiness. See
218				 * copy_nonpresent_pte() for explanation.
219				 */
220				entry = make_readable_device_private_entry(
221							swp_offset(entry));
222				newpte = swp_entry_to_pte(entry);
223				if (pte_swp_uffd_wp(oldpte))
224					newpte = pte_swp_mkuffd_wp(newpte);
225			} else if (is_writable_device_exclusive_entry(entry)) {
226				entry = make_readable_device_exclusive_entry(
227							swp_offset(entry));
228				newpte = swp_entry_to_pte(entry);
229				if (pte_swp_soft_dirty(oldpte))
230					newpte = pte_swp_mksoft_dirty(newpte);
231				if (pte_swp_uffd_wp(oldpte))
232					newpte = pte_swp_mkuffd_wp(newpte);
233			} else if (is_pte_marker_entry(entry)) {
234				/*
235				 * Ignore error swap entries unconditionally,
236				 * because any access should sigbus anyway.
237				 */
238				if (is_poisoned_swp_entry(entry))
239					continue;
240				/*
241				 * If this is uffd-wp pte marker and we'd like
242				 * to unprotect it, drop it; the next page
243				 * fault will trigger without uffd trapping.
244				 */
245				if (uffd_wp_resolve) {
246					pte_clear(vma->vm_mm, addr, pte);
247					pages++;
248				}
249				continue;
250			} else {
251				newpte = oldpte;
252			}
253
254			if (uffd_wp)
255				newpte = pte_swp_mkuffd_wp(newpte);
256			else if (uffd_wp_resolve)
257				newpte = pte_swp_clear_uffd_wp(newpte);
258
259			if (!pte_same(oldpte, newpte)) {
260				set_pte_at(vma->vm_mm, addr, pte, newpte);
261				pages++;
262			}
263		} else {
264			/* It must be an none page, or what else?.. */
265			WARN_ON_ONCE(!pte_none(oldpte));
266
267			/*
268			 * Nobody plays with any none ptes besides
269			 * userfaultfd when applying the protections.
270			 */
271			if (likely(!uffd_wp))
272				continue;
273
274			if (userfaultfd_wp_use_markers(vma)) {
275				/*
276				 * For file-backed mem, we need to be able to
277				 * wr-protect a none pte, because even if the
278				 * pte is none, the page/swap cache could
279				 * exist.  Doing that by install a marker.
280				 */
281				set_pte_at(vma->vm_mm, addr, pte,
282					   make_pte_marker(PTE_MARKER_UFFD_WP));
283				pages++;
284			}
285		}
286	} while (pte++, addr += PAGE_SIZE, addr != end);
287	arch_leave_lazy_mmu_mode();
288	pte_unmap_unlock(pte - 1, ptl);
289
290	return pages;
291}
292
293/*
294 * Return true if we want to split THPs into PTE mappings in change
295 * protection procedure, false otherwise.
296 */
297static inline bool
298pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags)
299{
300	/*
301	 * pte markers only resides in pte level, if we need pte markers,
302	 * we need to split.  We cannot wr-protect shmem thp because file
303	 * thp is handled differently when split by erasing the pmd so far.
304	 */
305	return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
306}
307
308/*
309 * Return true if we want to populate pgtables in change protection
310 * procedure, false otherwise
311 */
312static inline bool
313pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags)
314{
315	/* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */
316	if (!(cp_flags & MM_CP_UFFD_WP))
317		return false;
318
319	/* Populate if the userfaultfd mode requires pte markers */
320	return userfaultfd_wp_use_markers(vma);
321}
322
323/*
324 * Populate the pgtable underneath for whatever reason if requested.
325 * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable
326 * allocation failures during page faults by kicking OOM and returning
327 * error.
328 */
329#define  change_pmd_prepare(vma, pmd, cp_flags)				\
330	({								\
331		long err = 0;						\
332		if (unlikely(pgtable_populate_needed(vma, cp_flags))) {	\
333			if (pte_alloc(vma->vm_mm, pmd))			\
334				err = -ENOMEM;				\
335		}							\
336		err;							\
337	})
338
339/*
340 * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
341 * have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
342 * while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
343 */
344#define  change_prepare(vma, high, low, addr, cp_flags)			\
345	  ({								\
346		long err = 0;						\
347		if (unlikely(pgtable_populate_needed(vma, cp_flags))) {	\
348			low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
349			if (p == NULL)					\
350				err = -ENOMEM;				\
351		}							\
352		err;							\
353	})
354
355static inline long change_pmd_range(struct mmu_gather *tlb,
356		struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
357		unsigned long end, pgprot_t newprot, unsigned long cp_flags)
358{
359	pmd_t *pmd;
360	unsigned long next;
361	long pages = 0;
362	unsigned long nr_huge_updates = 0;
363	struct mmu_notifier_range range;
364
365	range.start = 0;
366
367	pmd = pmd_offset(pud, addr);
368	do {
369		long ret;
370		pmd_t _pmd;
371again:
372		next = pmd_addr_end(addr, end);
373
374		ret = change_pmd_prepare(vma, pmd, cp_flags);
375		if (ret) {
376			pages = ret;
377			break;
378		}
379
380		if (pmd_none(*pmd))
381			goto next;
382
383		/* invoke the mmu notifier if the pmd is populated */
384		if (!range.start) {
385			mmu_notifier_range_init(&range,
386				MMU_NOTIFY_PROTECTION_VMA, 0,
387				vma->vm_mm, addr, end);
388			mmu_notifier_invalidate_range_start(&range);
389		}
390
391		_pmd = pmdp_get_lockless(pmd);
392		if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) {
393			if ((next - addr != HPAGE_PMD_SIZE) ||
394			    pgtable_split_needed(vma, cp_flags)) {
395				__split_huge_pmd(vma, pmd, addr, false, NULL);
396				/*
397				 * For file-backed, the pmd could have been
398				 * cleared; make sure pmd populated if
399				 * necessary, then fall-through to pte level.
400				 */
401				ret = change_pmd_prepare(vma, pmd, cp_flags);
402				if (ret) {
403					pages = ret;
404					break;
405				}
406			} else {
407				ret = change_huge_pmd(tlb, vma, pmd,
408						addr, newprot, cp_flags);
409				if (ret) {
410					if (ret == HPAGE_PMD_NR) {
411						pages += HPAGE_PMD_NR;
412						nr_huge_updates++;
413					}
414
415					/* huge pmd was handled */
416					goto next;
417				}
418			}
419			/* fall through, the trans huge pmd just split */
420		}
421
422		ret = change_pte_range(tlb, vma, pmd, addr, next, newprot,
423				       cp_flags);
424		if (ret < 0)
425			goto again;
426		pages += ret;
427next:
428		cond_resched();
429	} while (pmd++, addr = next, addr != end);
430
431	if (range.start)
432		mmu_notifier_invalidate_range_end(&range);
433
434	if (nr_huge_updates)
435		count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
436	return pages;
437}
438
439static inline long change_pud_range(struct mmu_gather *tlb,
440		struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
441		unsigned long end, pgprot_t newprot, unsigned long cp_flags)
442{
443	pud_t *pud;
444	unsigned long next;
445	long pages = 0, ret;
446
447	pud = pud_offset(p4d, addr);
448	do {
449		next = pud_addr_end(addr, end);
450		ret = change_prepare(vma, pud, pmd, addr, cp_flags);
451		if (ret)
452			return ret;
453		if (pud_none_or_clear_bad(pud))
454			continue;
455		pages += change_pmd_range(tlb, vma, pud, addr, next, newprot,
456					  cp_flags);
457	} while (pud++, addr = next, addr != end);
458
459	return pages;
460}
461
462static inline long change_p4d_range(struct mmu_gather *tlb,
463		struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
464		unsigned long end, pgprot_t newprot, unsigned long cp_flags)
465{
466	p4d_t *p4d;
467	unsigned long next;
468	long pages = 0, ret;
469
470	p4d = p4d_offset(pgd, addr);
471	do {
472		next = p4d_addr_end(addr, end);
473		ret = change_prepare(vma, p4d, pud, addr, cp_flags);
474		if (ret)
475			return ret;
476		if (p4d_none_or_clear_bad(p4d))
477			continue;
478		pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
479					  cp_flags);
480	} while (p4d++, addr = next, addr != end);
481
482	return pages;
483}
484
485static long change_protection_range(struct mmu_gather *tlb,
486		struct vm_area_struct *vma, unsigned long addr,
487		unsigned long end, pgprot_t newprot, unsigned long cp_flags)
488{
489	struct mm_struct *mm = vma->vm_mm;
490	pgd_t *pgd;
491	unsigned long next;
492	long pages = 0, ret;
493
494	BUG_ON(addr >= end);
495	pgd = pgd_offset(mm, addr);
496	tlb_start_vma(tlb, vma);
497	do {
498		next = pgd_addr_end(addr, end);
499		ret = change_prepare(vma, pgd, p4d, addr, cp_flags);
500		if (ret) {
501			pages = ret;
502			break;
503		}
504		if (pgd_none_or_clear_bad(pgd))
505			continue;
506		pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
507					  cp_flags);
508	} while (pgd++, addr = next, addr != end);
509
510	tlb_end_vma(tlb, vma);
511
512	return pages;
513}
514
515long change_protection(struct mmu_gather *tlb,
516		       struct vm_area_struct *vma, unsigned long start,
517		       unsigned long end, unsigned long cp_flags)
518{
519	pgprot_t newprot = vma->vm_page_prot;
520	long pages;
521
522	BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
523
524#ifdef CONFIG_NUMA_BALANCING
525	/*
526	 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking)
527	 * are expected to reflect their requirements via VMA flags such that
528	 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly.
529	 */
530	if (cp_flags & MM_CP_PROT_NUMA)
531		newprot = PAGE_NONE;
532#else
533	WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA);
534#endif
535
536	if (is_vm_hugetlb_page(vma))
537		pages = hugetlb_change_protection(vma, start, end, newprot,
538						  cp_flags);
539	else
540		pages = change_protection_range(tlb, vma, start, end, newprot,
541						cp_flags);
542
543	return pages;
544}
545
546static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
547			       unsigned long next, struct mm_walk *walk)
548{
549	return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
550				  *(pgprot_t *)(walk->private)) ?
551		0 : -EACCES;
552}
553
554static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
555				   unsigned long addr, unsigned long next,
556				   struct mm_walk *walk)
557{
558	return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
559				  *(pgprot_t *)(walk->private)) ?
560		0 : -EACCES;
561}
562
563static int prot_none_test(unsigned long addr, unsigned long next,
564			  struct mm_walk *walk)
565{
566	return 0;
567}
568
569static const struct mm_walk_ops prot_none_walk_ops = {
570	.pte_entry		= prot_none_pte_entry,
571	.hugetlb_entry		= prot_none_hugetlb_entry,
572	.test_walk		= prot_none_test,
573	.walk_lock		= PGWALK_WRLOCK,
574};
575
576int
577mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
578	       struct vm_area_struct *vma, struct vm_area_struct **pprev,
579	       unsigned long start, unsigned long end, unsigned long newflags)
580{
581	struct mm_struct *mm = vma->vm_mm;
582	unsigned long oldflags = vma->vm_flags;
583	long nrpages = (end - start) >> PAGE_SHIFT;
584	unsigned int mm_cp_flags = 0;
585	unsigned long charged = 0;
586	int error;
587
588	if (newflags == oldflags) {
589		*pprev = vma;
590		return 0;
591	}
592
593	/*
594	 * Do PROT_NONE PFN permission checks here when we can still
595	 * bail out without undoing a lot of state. This is a rather
596	 * uncommon case, so doesn't need to be very optimized.
597	 */
598	if (arch_has_pfn_modify_check() &&
599	    (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
600	    (newflags & VM_ACCESS_FLAGS) == 0) {
601		pgprot_t new_pgprot = vm_get_page_prot(newflags);
602
603		error = walk_page_range(current->mm, start, end,
604				&prot_none_walk_ops, &new_pgprot);
605		if (error)
606			return error;
607	}
608
609	/*
610	 * If we make a private mapping writable we increase our commit;
611	 * but (without finer accounting) cannot reduce our commit if we
612	 * make it unwritable again except in the anonymous case where no
613	 * anon_vma has yet to be assigned.
614	 *
615	 * hugetlb mapping were accounted for even if read-only so there is
616	 * no need to account for them here.
617	 */
618	if (newflags & VM_WRITE) {
619		/* Check space limits when area turns into data. */
620		if (!may_expand_vm(mm, newflags, nrpages) &&
621				may_expand_vm(mm, oldflags, nrpages))
622			return -ENOMEM;
623		if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
624						VM_SHARED|VM_NORESERVE))) {
625			charged = nrpages;
626			if (security_vm_enough_memory_mm(mm, charged))
627				return -ENOMEM;
628			newflags |= VM_ACCOUNT;
629		}
630	} else if ((oldflags & VM_ACCOUNT) && vma_is_anonymous(vma) &&
631		   !vma->anon_vma) {
632		newflags &= ~VM_ACCOUNT;
633	}
634
635	vma = vma_modify_flags(vmi, *pprev, vma, start, end, newflags);
636	if (IS_ERR(vma)) {
637		error = PTR_ERR(vma);
638		goto fail;
639	}
640
641	*pprev = vma;
642
643	/*
644	 * vm_flags and vm_page_prot are protected by the mmap_lock
645	 * held in write mode.
646	 */
647	vma_start_write(vma);
648	vm_flags_reset(vma, newflags);
649	if (vma_wants_manual_pte_write_upgrade(vma))
650		mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
651	vma_set_page_prot(vma);
652
653	change_protection(tlb, vma, start, end, mm_cp_flags);
654
655	if ((oldflags & VM_ACCOUNT) && !(newflags & VM_ACCOUNT))
656		vm_unacct_memory(nrpages);
657
658	/*
659	 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
660	 * fault on access.
661	 */
662	if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
663			(newflags & VM_WRITE)) {
664		populate_vma_page_range(vma, start, end, NULL);
665	}
666
667	vm_stat_account(mm, oldflags, -nrpages);
668	vm_stat_account(mm, newflags, nrpages);
669	perf_event_mmap(vma);
670	return 0;
671
672fail:
673	vm_unacct_memory(charged);
674	return error;
675}
676
677/*
678 * pkey==-1 when doing a legacy mprotect()
679 */
680static int do_mprotect_pkey(unsigned long start, size_t len,
681		unsigned long prot, int pkey)
682{
683	unsigned long nstart, end, tmp, reqprot;
684	struct vm_area_struct *vma, *prev;
685	int error;
686	const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
687	const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
688				(prot & PROT_READ);
689	struct mmu_gather tlb;
690	struct vma_iterator vmi;
691
692	start = untagged_addr(start);
693
694	prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
695	if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
696		return -EINVAL;
697
698	if (start & ~PAGE_MASK)
699		return -EINVAL;
700	if (!len)
701		return 0;
702	len = PAGE_ALIGN(len);
703	end = start + len;
704	if (end <= start)
705		return -ENOMEM;
706	if (!arch_validate_prot(prot, start))
707		return -EINVAL;
708
709	reqprot = prot;
710
711	if (mmap_write_lock_killable(current->mm))
712		return -EINTR;
713
714	/*
715	 * If userspace did not allocate the pkey, do not let
716	 * them use it here.
717	 */
718	error = -EINVAL;
719	if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
720		goto out;
721
722	vma_iter_init(&vmi, current->mm, start);
723	vma = vma_find(&vmi, end);
724	error = -ENOMEM;
725	if (!vma)
726		goto out;
727
728	if (unlikely(grows & PROT_GROWSDOWN)) {
729		if (vma->vm_start >= end)
730			goto out;
731		start = vma->vm_start;
732		error = -EINVAL;
733		if (!(vma->vm_flags & VM_GROWSDOWN))
734			goto out;
735	} else {
736		if (vma->vm_start > start)
737			goto out;
738		if (unlikely(grows & PROT_GROWSUP)) {
739			end = vma->vm_end;
740			error = -EINVAL;
741			if (!(vma->vm_flags & VM_GROWSUP))
742				goto out;
743		}
744	}
745
746	prev = vma_prev(&vmi);
747	if (start > vma->vm_start)
748		prev = vma;
749
750	tlb_gather_mmu(&tlb, current->mm);
751	nstart = start;
752	tmp = vma->vm_start;
753	for_each_vma_range(vmi, vma, end) {
754		unsigned long mask_off_old_flags;
755		unsigned long newflags;
756		int new_vma_pkey;
757
758		if (vma->vm_start != tmp) {
759			error = -ENOMEM;
760			break;
761		}
762
763		/* Does the application expect PROT_READ to imply PROT_EXEC */
764		if (rier && (vma->vm_flags & VM_MAYEXEC))
765			prot |= PROT_EXEC;
766
767		/*
768		 * Each mprotect() call explicitly passes r/w/x permissions.
769		 * If a permission is not passed to mprotect(), it must be
770		 * cleared from the VMA.
771		 */
772		mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR;
773
774		new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
775		newflags = calc_vm_prot_bits(prot, new_vma_pkey);
776		newflags |= (vma->vm_flags & ~mask_off_old_flags);
777
778		/* newflags >> 4 shift VM_MAY% in place of VM_% */
779		if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
780			error = -EACCES;
781			break;
782		}
783
784		if (map_deny_write_exec(vma, newflags)) {
785			error = -EACCES;
786			break;
787		}
788
789		/* Allow architectures to sanity-check the new flags */
790		if (!arch_validate_flags(newflags)) {
791			error = -EINVAL;
792			break;
793		}
794
795		error = security_file_mprotect(vma, reqprot, prot);
796		if (error)
797			break;
798
799		tmp = vma->vm_end;
800		if (tmp > end)
801			tmp = end;
802
803		if (vma->vm_ops && vma->vm_ops->mprotect) {
804			error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
805			if (error)
806				break;
807		}
808
809		error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags);
810		if (error)
811			break;
812
813		tmp = vma_iter_end(&vmi);
814		nstart = tmp;
815		prot = reqprot;
816	}
817	tlb_finish_mmu(&tlb);
818
819	if (!error && tmp < end)
820		error = -ENOMEM;
821
822out:
823	mmap_write_unlock(current->mm);
824	return error;
825}
826
827SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
828		unsigned long, prot)
829{
830	return do_mprotect_pkey(start, len, prot, -1);
831}
832
833#ifdef CONFIG_ARCH_HAS_PKEYS
834
835SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
836		unsigned long, prot, int, pkey)
837{
838	return do_mprotect_pkey(start, len, prot, pkey);
839}
840
841SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
842{
843	int pkey;
844	int ret;
845
846	/* No flags supported yet. */
847	if (flags)
848		return -EINVAL;
849	/* check for unsupported init values */
850	if (init_val & ~PKEY_ACCESS_MASK)
851		return -EINVAL;
852
853	mmap_write_lock(current->mm);
854	pkey = mm_pkey_alloc(current->mm);
855
856	ret = -ENOSPC;
857	if (pkey == -1)
858		goto out;
859
860	ret = arch_set_user_pkey_access(current, pkey, init_val);
861	if (ret) {
862		mm_pkey_free(current->mm, pkey);
863		goto out;
864	}
865	ret = pkey;
866out:
867	mmap_write_unlock(current->mm);
868	return ret;
869}
870
871SYSCALL_DEFINE1(pkey_free, int, pkey)
872{
873	int ret;
874
875	mmap_write_lock(current->mm);
876	ret = mm_pkey_free(current->mm, pkey);
877	mmap_write_unlock(current->mm);
878
879	/*
880	 * We could provide warnings or errors if any VMA still
881	 * has the pkey set here.
882	 */
883	return ret;
884}
885
886#endif /* CONFIG_ARCH_HAS_PKEYS */
887